OCT Workpiece Position Sensing for CAD-Aligned Machining Paths

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Solution Overview

Problem

Current methods for determining the position and orientation of a workpiece in machining processes, such as laser processing, require manual teaching and are time-consuming, lacking an efficient automated solution.

Innovation Solution

The method employs optical coherence tomography (OCT) for automated scanning to determine the workpiece's position and features, allowing for automatic recording and machining without manual teaching, using an OCT measuring beam to guide the machining head and transform machining paths from a CAD model to the actual workpiece position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual teaching is used to determine workpiece position and orientation, then the workpiece can be positioned and oriented in the workspace, but the process is time-consuming and reduces productivity

Engineering Contradiction:
Improveworkpiece position and orientation determinationVSAvoidprogramming time
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent replaces manual mechanical teaching operations with automated optical measurement using OCT technology. The OCT measuring beam automatically scans the workpiece to determine its position and orientation, eliminating the need for manual operator intervention and significantly reducing programming time while maintaining measurement precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The workpiece itself serves as the measurement target for the OCT system. By scanning the workpiece geometry directly, the system automatically determines position and orientation without requiring external fixtures or manual reference points, enabling self-positioning and reducing setup time.

Inventive Principle:
Principle #25Self-service

2Productivity

If automated scanning with OCT is implemented, then productivity and speed are improved, but the device complexity increases due to integration of OCT system with machining head

Engineering Contradiction:
Improveautomated workpiece positioningVSAvoidmachining head structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent combines the OCT measuring system and the machining head into a single integrated unit. The OCT measuring beam is guided over the machining head, and both components are controlled by a unified control unit. This merging reduces the number of separate devices and interfaces, simplifying the overall system despite the advanced functionality.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The integrated machining head serves multiple functions: it performs both OCT-based measurement/scan operations and actual machining operations. The single device can switch between measurement mode and machining mode, eliminating the need for separate measurement and machining equipment, thereby reducing overall system complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Measurement precision

If OCT measuring beam is guided over machining head, then measurement accuracy is improved, but the loss of time for scanning increases

Engineering Contradiction:
Improveworkpiece feature detectionVSAvoidscanning time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The OCT measuring beam continuously scans the workpiece surface during the positioning process, maintaining constant measurement activity without interruptions. The control unit processes measurement data in real-time, allowing the scanning operation to proceed continuously and efficiently, minimizing total scanning time while ensuring complete coverage for accurate feature detection.

Inventive Principle:
Principle #20Continuity of useful action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach eliminates the need for manual teaching, reduces processing time, lowers the risk of incorrect operation, enables offline programming for robots, and simplifies machine construction by allowing for repeatable workpiece positioning, resulting in faster and more accurate machining.

Implementation Method 1

The OCT measuring method is used to automatically measure features of a workpiece to be machined... based on distance measurement values of the optical coherence tomograph determined during automated scanning

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

automated scanning of a workpiece to be machined arranged in the work area by means of an OCT measuring beam of an optical coherence tomograph

Methodology Applied
Scientific EffectOptical coherence tomography: Tomography

Data Source

PatentEP4132738B1Method, machine tool and computer program for sensing a workpiece position by means of oct
Publication Date: 2024.12.04 TRUMPF LASER SE
  • EP4132738B1 patent drawingFigure 1

AI summary

This application relates to a method for machining a workpiece (1) by means of a machining beam (3), which exits from a machining head (20). The workpiece (5) and the machining head (20) can be moved relative to each other in a working space. The method comprises the following method steps: - automated scanning of a workpiece (5), which is arranged in the working space and is to be machined, by means of an OCT measurement beam (11) of an optical coherence tomograph (6), which OCT measurement beam is guided through the machining head (20), the position of the machining head (20) in the working space and the position of the OCT measurement beam (11) relative to the machining head (20) both being known; - determining the position, in the working space, of the workpiece (5) to be machined on the basis of distance measurement values of the optical coherence tomograph (6) which were ascertained in the automated scanning; - ascertaining a coordinate transformation (T) between the determined workpiece position and the position of a CAD model (23) of the workpiece (5) to be machined in a CAD coordinate system (24); - transforming a machining path of the machining head (20) and of the machining beam (3), which machining path is programmed for the CAD model (23) in the CAD coordinate system (24), to the determined position of the workpiece (5) to be machined by means of the ascertained coordinate transformation (T); and - machining the workpiece (5) by means of the machining beam (3) by moving the machining head (20) and the machining beam (3) relative to each other along the transformed machining path.